Supreme Court Justice Sandra Day O'Connor (search), the first woman to serve on the nation's highest court, submitted a letter of retirement to President Bush on Friday, setting the stage for a contentious battle over her replacement.

O'Connor — who often provided the deciding, or swing, vote in Supreme Court (search) decisions — will step down from the bench upon the appointment of her successor.

"It has been a great privilege indeed to have served as a member of the court for 24 terms," O'Connor wrote in the one-paragraph resignation letter. "I will leave it with enormous respect for the integrity of the court and its role under our constitutional structure."

She told the president and associates that she wanted to spend more time with her family. Her husband has been in failing health in recent years.

Click here to read O'Connor's retirement letter to President Bush.

Bush formally announced her retirement in the White House Rose Garden Friday morning, saying he'd just had a "warm" telephone conversation with O'Connor.

"America is proud of Justice O’Connor’s distinguished service, and I’m proud to know her," Bush said. "She has been a discerning and conscientious judge, and a public servant of complete integrity."

He did not mention a potential successor for O'Connor during the brief news conference, but said he would take the responsibility to replace her "seriously" and would choose a nominee in a "timely manner," with plans to submit a nomination to the Senate for a vote before the Supreme Court's new term starts in October.

Bush said he and his administration would consult with lawmakers, and said "the nation deserves a dignified" confirmation debate.

"But today is a day to honor the contributions of a fine citizen and a great patriot," Bush said. "Americans had high expectations of her. She has surpassed those expectations. Our nation is deeply grateful."

O'Connor, 75, has served on the Supreme Court for 24 years and was appointed in 1981 by President Ronald Reagan. Her departure creates the first vacancy on the court in the past 11 years and represents the first chance Bush has had to nominate a justice.

Over time, O'Connor evolved into a moderate conservative, but more importantly, a majority maker.

She voted with a 5-4 majority, for example, on the case that effectively awarded the disputed 2000 presidential election to Bush. She was on the winning side again when the court upheld the right of women to have an abortion if their health were in danger.

She expressed her views pungently at times. Last week, in a dissent in a 5-4 ruling that let local governments take personal property to build malls and other businesses, she wrote that the majority had unwisely handed more power to the powerful.

"The specter of condemnation hangs over all property," O'Connor wrote. "Nothing is to prevent the state from replacing ... any home with a shopping mall, or any farm with a factory."

The Supreme Court ended its latest session on Monday, and speculation this week has focused on the possible resignation of Chief Justice William Rehnquist (search). But so far, Rehnquist has remained.

O'Connor was often the deciding vote in a string of 5-4 decisions coming from the bench, sometimes siding with the conservative wing and other times with the liberal contingent.

"She is a swing vote and it's really hard to predict where she comes down on any particular case," Robert Bork, a controversial nominee to the Supreme Court who was denied a chance to serve, told FOX News.

Lawmakers praised O'Connor's service.

"She was a careful and thoughtful and highly respected member of the court, a wise judge who served the nation and the constitution well," Sen. Ted Kennedy, D-Mass., said. "I hope the president will select someone who meets the high standards that she set, and that can bring the nation together as she did."

"Throughout her service on the nation's highest court, Justice O'Connor restored a measure of common sense to our criminal justice system, a measure of respect for our nation's allocation of power between the states and the federal government, and a measure of freedom in the public square to people of faith," Senate Judiciary Committee member Sen. John Cornyn, R-Texas, said in a statement.

'Reflections of a Supreme Court Justice'

Two years ago, O'Connor wrote the book "The Majesty of the Law: Reflections of a Supreme Court Justice," which was partly a personal account of her experiences as the first woman named to the high court and partly a historical look at the development of U.S. law.

"It's been something that opens so many doors for other women that it really is a joy to know that it did happen and that it had such an effect," O'Connor told FOX News in a 2003 interview.

Having women and minorities on the court helps the public accept Supreme Court rulings, O'Connor said in a 2003 Associated Press interview.

"It's not for me to say," whether racial, ethnic or gender diversity on the court should be a goal, she said. "But I think it's been desirable from the standpoint of public perceptions of fairness to see a court that includes women and minorities."

O'Connor was a politician and a state trial judge in Arizona before President Reagan chose her for the high court in 1981. She drew on her experience as a judge for a section of the book dealing with juries.

Jurors ought to be free to take notes during a trial, and even pose written questions, O'Connor said. Only some states and courts allow such departures from custom.

O'Connor tried to instruct her juries about the law at the beginning of the case rather than at the end, she said.

"It seems to me when I listen to complicated things it helps me to know ahead of time what I'm supposed to decide," O'Connor said. "I can hear the arguments to better effect, and I think jurors can hear the facts more effectively if they know ahead of time what specifically they have to decide."

Her book contains some strong criticism of the way juries are now chosen, including the reliance on outside jury consultants that some believe "can virtually guarantee a verdict by stacking the jury with people who fit the ideal demographic profile."

Even so, O'Connor said in the interview, she does not blame defense lawyers for using whatever tools are available to them.

"Yet people who can't afford it are not going to have that benefit, and you get a little nervous about how that might play out in terms of fairness," O'Connor said.

One of the court's two swing votes, O'Connor often sides with more conservative justices as she did in the Bush v. Gore ruling in 2000. Although some lawyers and Republicans have said that ruling did not really decide the election, O'Connor does not mince words in a brief reference to the case in her book.

Bush v. Gore, she said, "held unconstitutional Florida's presidential election recount procedures, and thereby determined the outcome of the election."

O'Connor said her tenure on the high court probably has not hastened the day when America will elect a woman president. But that day is inevitable, she said.

The Supreme Court has no "overarching objective" when it comes to the death penalty, despite a large number of recent cases wrestling with the way capital punishment is carried out, Justice Sandra Day O'Connor says.

O'Connor was in the majority when the high court outlawed capital punishment for the mentally retarded, but in the minority when justices ruled that juries, not judges, must make the crucial decisions that can lead to a death sentence.

"We aren't here trying to develop something in the sense of where the country should go with this issue. We're a reactive institution," O'Connor said in an Associated Press interview Monday. "We proceed case by case as they come to us, and not with any overarching objective that the court itself" has developed.

FOX News' Catherine Donaldson-Evans, Megyn Kendall and The Associated Press contributed to this report.